New metabolites of riboflavin appeared in rat urine

By using paper and silica gel thin layer chromatography with various solvent systems, flavin compounds appeared in rat urine after administration of radioactive riboflavin were analyzed in detail. Two new metabolites having radioactivity were separated and their structures were determined to be 7-carboxy lumichrome and 8-carboxy lumichrome. The sum of radioactivities of these two compounds was about 46% of total radioactivity excreted in the urine during 24 h.